System and method for sensor-based dynamic lighting output generation and modification

ABSTRACT

A digitally controlled LED illuminator sheet that produces far-field illumination patterns or light field distributions that increase light utilization and application efficiency. A dynamic directional LEDs (or other kinds of solid-state light sources) sheet is positioned under each lenslet of a microlens array. Individual LED beam pointing direction depends on off-axis position relative to optical axis of lenslet. Individual beams from independent LEDs form illumination pixels at the illumination plane or within a volume space and can be modulated in intensity. Illumination pixels partially overlap in far-field illumination plane and illumination volume. Data from sensors can be collected and the LEDs can be digitally turned on or off and/or pulse width or amplitude modulated based on sensor data to produce far-field illumination patterns or light field distributions with spectral efficiency and efficacious intensity.

FIELD

This application relates in general to lighting, and in particular, to asystem and method for sensor-based dynamic lighting output generationand modification.

BACKGROUND

Electrical lighting is the most common form of artificial lighting inindustrial societies and is essential for enabling activities after darkand in environments where natural light is not sufficient. As a result,electrical lighting is a significant source of electricity consumption,with one estimate placing 15 commercial sector lighting electricityconsumption at 12% of total commercial sector electricity consumption in2020. Considering the amount of electrical energy consumed, efficiency,convenience, and cost of lighting systems becomes particular important,with lighting application efficiency being a new frontier for futurelighting energy savings.

Unfortunately, current electrical lighting, and commercial electricallighting in particular, is rather inefficient. For instance, commerciallighting is static and provides flood illumination, covering areas thatmay or may not need light, thus wasting electrical energy.

Current solutions for improving the light application efficiency (LAE)of lighting systems, particularly commercial lighting systems, haveproved inadequate due to either inadequate efficiency, difficulty indirecting the light at a desired direction and not to a location whereno light is needed, not providing the spectral power distribution thatis most advantageous for the human visual system, not delivering anefficacious light intensity for a particular environment, or theirexpense. For example, commercial lighting sources are generally solidstate light (SSL) sources: light sources that utilize semiconductorlight-emitting diodes (LEDs), polymer light-emitting diodes (PLED), ororganic light-emitting diodes (OLED) lights as sources of illumination.However, traditional solid state light (SSL) sources have keydisadvantages, such as being thick, heavy, requiring expensiveinsulation and drilling holes in ceilings for installation, not beingcustomizable (such as being limited to strut layouts), having largethermal cooling requirements, and not being bendable, thus limiting theplacement of such light systems.

Thin lighting sheets (thin, flexible sheets on which LEDs or OLEDs aremounted) overcome the disadvantages of some of the traditional SSLsources relating to the difficulty of their placement and servicing.However, existing thin light sheets are not dynamic, being able toprovide only the same amount of light in the same direction unless theyare repositioned, and have other shortcomings. For example, in the caseof organic light-emitting diodes (OLED) being used in thin light sheets,such light sheets tend to be expensive, have low efficiency, lowreliability, do not allow for sensor (or other electronic device)integration, and do not allow for creation of affordable custom shapes.Similarly, thin sheets distributed by NthDegree Technologies Worldwide,Inc. of Tempe, Ariz., United States do not allow for full utilization ofthe LED lights in the sheets and tend to produce aestheticallyunpleasing speckles or bright glare spots.

Likewise, Edge-Lit™ light pipes distributed by Fusion® Optics attempt toaddress the low efficiency of lighting systems. However, such pipes arethick, allow for limited spatial control, and do not allow integrationof sensors or other electronic devices.

Finally, Glint Photonics, Inc. of Burlingame, Calif., United States,distributes Hero™ luminaires, the direction of whose light can beadjusted with a joystick while the luminaire remains in a fixed positionand orientation. However, such luminaires have a high glare, and requiremoving mechanical parts to point the light in different directions.Dynamic light projection sources distributed by Lumileds Holding B.V. ofSchipol, Netherlands suffer from a similar drawback of having a highglare.

Therefore, there is a need for a high efficiency lighting system that islow glare, flexible, delivers light to where the light is needed, has asuitable spectral distribution, provides effective intensity levels, andis easily customizable.

SUMMARY

A digitally-controlled LED illuminator sheet is provided that producesfar-field illumination patterns or light field distributions and thatimproves light utilization. A dynamic directional solid-state lightingsheet that utilizes LEDs (or other kinds of solid-state light sources)positioned under each lenslet of a microlens array. Individual LED beampointing direction depends on off-axis position relative to optical axisof lenslet. Individual beams from independent LEDs form illuminationpixels at the illumination plane or within a volume space and can bemodulated in intensity. Illumination pixels partially overlap infar-field illumination plane and illumination volume. Over a largeillumination space many illumination pixels will partially superimposedon neighboring illumination pixels, with the overlap being in incrementsmuch smaller than the size of an illumination pixel. The LEDs can bedigitally turned on or off and/or pulse width or amplitude modulated toproduce digitally controlled far-field illumination patterns or lightfield distributions. The LEDs and lenslets are so closely spacedtogether that, at normal viewing distance, they appear like a diffusecontinuous pattern instead of a pattern of individual bright spots. Thisproperty is responsible for the reduced glare. The LEDs can also havedifferent spectral characteristics relative to one another, which wouldenable tailoring of the spectral power distribution of the illuminationdigitally by turning on certain LEDs at various levels of intensity.

In one embodiment, a system for sensor-based dynamic lighting output isprovided. The system includes a microlens array includes a plurality oflenslets; an array of solid state light sources aligned with each of thelenslets; one or more sensors configured to collect data; a computer incontrol of each of the light sources and interfaced to the one or moresensors, the computer including at least one processor, the computerconfigured to: obtain a desired illumination pattern including at leastone of a desired far-field illumination pattern and a desired lightfield distribution; identify based on at least some of the sensor datathose of the light sources that need to be turned on to generate thedesired illumination pattern; and control the identified light sourcesto generate the desired illumination pattern.

In a further embodiment, a system for sensor-based lighting outputgeneration and modification is provided. The system includes a microlensarray includes a plurality of lenslets; an array of solid state lightsources aligned with each of the lenslets; one or more sensorsconfigured to collect data; a computer in control of each of the lightsources and interfaced to the one or more sensors, the computerincluding at least one processor, the computer configured to: obtain adesired illumination pattern including at least one of a desiredfar-field illumination pattern and a desired light field distribution;identify those of the light sources that need to be turned on togenerate the desired illumination pattern; command the identified lightsources to turn on to generate the desired illumination pattern; detectusing at least some of the sensor data that an illumination patterngenerated by the commanded light sources differs from the desiredillumination pattern; and adjust which of the lights sources are turnedon based on the detection and at least some of the sensor data.

In a still further embodiment, a system for sensor-based lighting outputintensity modulation is provided. The system includes a microlens arrayincludes a plurality of lenslets; an array of solid state light sourcesaligned with each of the lenslets; one or more sensors configured tocollect data; a computer in control of each of the light sources andinterfaced to the one or more sensors, the computer including at leastone processor, the computer configured to: obtain a desired illuminationpattern including at least one of a desired far-field illuminationpattern and a desired light field distribution; identify those of thelight sources that need to be turned on to generate the desiredillumination pattern; command the identified light sources to turn on toprovide light to generate the desired illumination pattern; modulate anintensity of the light generated by the commanded light sources based onat least some of the sensor data.

Still other embodiments of the present invention will become readilyapparent to those skilled in the art from the following detaileddescription, wherein is described embodiments of the invention by way ofillustrating the best mode contemplated for carrying out the invention.As will be realized, the invention is capable of other and differentembodiments and its several details are capable of modifications invarious obvious respects, all without departing from the spirit and thescope of the present invention. Accordingly, the drawings and detaileddescription are to be regarded as illustrative in nature and not asrestrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a system 10 for light field illuminatorsheet-based dynamic lighting output in accordance with one embodiment.

FIGS. 2A-2B is a diagram illustrating two groups of arrays in accordancewith two embodiments.

FIGS. 3A-3B are diagrams showing front (the side facing the lenslets)and back (the side facing the LEDs) of a pyramidal, reflective,honeycomb-shaped spacer 25 in accordance with one embodiment.

FIG. 4 is a diagram illustrating the pointing angle and the divergenceangle.

FIGS. 5A-5F show, for purposes of illustration, different illuminationpatterns created through overlapping of illumination pixels.

FIG. 6A is an illustration of a ray trace created by a small section ofthe sheet when all LEDS in that section of the sheet are on.

FIG. 6B is an illustration of a ray trace created by a small section ofthe sheet when only on-axis LEDs are on.

FIGS. 6C and 6D are illustrations of ray traces created by a smallsection of the sheet when only off-axis LEDs in that section are on.

FIGS. 6E and 6F are illustrations of ray traces created by a smallsection of the sheet when all LEDs are on in Far-Field.

FIG. 6H is an illustration of ray traces created by a small section ofthe sheet by off-axis LEDs in that section in the Far-Field region.

FIG. 6I is an illustration of a ray trace with a presence of a low-levelartifact created by a small section of the sheet.

FIG. 7 illustrates an example of conventional beam steering (prior art),which has high glare and requires the use of moving mechanical parts.

FIG. 8 illustrates an example of light shifting (prior art), which hashigh glare and requires the use of moving mechanical parts.

FIG. 9 is an illustration of dynamic light sheets achievable using thesystem, which has an improved light application efficiency (LAE) with nomoving parts and lower glare compared to the techniques illustrated withreference to FIGS. 7 and 8 .

FIG. 10 shows an expanded view of a light sheet including the spacer andthe back reflector and with LEDs being integrated into an LED plane inaccordance with one embodiment.

FIG. 11 shows the light sheet of FIG. 10 with the LEDs emitting light.

FIGS. 12A-B show simulated irradiance patterns achieved using threelight sheet tiles that included the reflective pyramidalhoneycomb-shaped spacer.

FIGS. 13A-B show simulated patterns, adjusted for human visualbrightness perception, achieved using three light sheet tiles thatincluded the reflective pyramidal honeycomb-shaped spacer and the backreflector.

FIG. 14 is a flow diagram showing a method for light field illuminatorsheet-based dynamic lighting control in accordance with one embodiment.

FIGS. 15A-15B are diagrams describing details of the particular lightsheet tiles used for an illumination simulation.

FIGS. 16A-16B are diagrams illustrating simulated illumination patternsachievable with three light sheet tiles of FIGS. 15A-15B.

FIGS. 17A-17B show simulated patterns, adjusted for human visualbrightness perception, achieved when all of the lights in the sheet areon (FIG. 17A) and when only a subset of the lights necessary to producethe checkerboard-like pattern are on (FIG. 17B).

FIG. 18 is a diagram showing a light beam pointing towards off-axislenslets in accordance with one embodiment.

DETAILED DESCRIPTION

Improved control over light distribution can be achieved through acombination of microlens arrays and computer-controlled LED arrays. FIG.1 is a diagram showing a system 10 for light field illuminatorsheet-based dynamic lighting output in accordance with one embodiment.The system 10 includes a light field illuminator sheet 30 (also referredto as a light sheet 30 and light sheet illumination tile 30 below),which in turn includes a microlens array 11, which includes a pluralityof microlenses 12 (also referred to as lenslets 12 below). The microlensarray 11 can include different types of lenslets 12 or combinations ofdifferent types of lenslets 12, with lenslets 12 being refractiveelements, Fresnel elements, off-axis elements, holographic opticalelements, diffractive optical elements, and reflective optical elements,though still other types of lenslets 12 are possible.

Aligned with each of the lenslets 12 is an array 13 of solid-statelights 14, each of the solid-state lighting arrays 13 being positionedunder one of the lenslets 13 relative to the orientation shown withreference to FIG. 1 . While in the description below, the array ofsolid-state lights 13 are referred to as an LED array 13, in a furtherembodiment, solid-state lights 13 other than LEDs could be used for inthe array 13, such as PLEDs or OLEDs are possible. In a still furtherembodiment, different kinds of solid-state lights 14 could be combinedin the same array 13. In a still further embodiment, arrays 13 withdifferent kinds of solid-state lights 14 could be aligned with differentones of the lenslets 12 in the microlens array 11. In one embodiment,the lenslets 12 can be near-hemispherical, though other shapes of thelenslets are also possible. For example, the lenslets 12 can bespherical, aspherical, cylindrical, acylindrical, toroidal, aspherictoroidal, or free-form surface shapes, though still other shapes of thelenslets 12 are possible. The lights 14 can have different spectralcharacteristics relative to one another. Such differences in spectralcharacteristics can include differences in spectral radiation bandwidth,spectral peak wavelength, and spectral power distribution, though otherspectral characteristics in which differences exist are also possible.In one embodiment, the lights 14 in the same array 13 can have the samespectral characteristics, and differences only exist between spectralcharacteristics of lights 14 that are in different arrays. In a furtherembodiment, lights 14 in the same array 13 can also have differences intheir spectral characteristics. In a still further embodiment, whiledifferences in spectral characteristics exist between lights 14 in thesame array 13, each array 13 could have lights 14 with the same spectralcharacteristics as in other arrays 13. The differences in spectralcharacteristics between the lights 14 enables tailoring of the spectralpower distribution of the illumination created by the system 10digitally by turning on certain lights at various levels of intensity,which in turn can increase the lighting application efficiency.

LEDs 14 can be arranged under microlens array 11 and individuallydigitally turned on or off to produce digitally controlled far-fieldillumination patterns. FIGS. 2A-2B is a diagram illustrating two groups23 of arrays 13 in accordance with two embodiments. Each of the groups23 is positioned to be aligned with a single microlens array 11. Whilein FIGS. 2A-2B, both the groups 23 and individual arrays 11 are shapedas squares, other shapes are possible. While the number of lights 14 ineach array 13 as seen with reference to FIGS. 2A-2B varies from 1 to 4,other numbers of lights 14 in each array 13 are possible. Using a singlelight 14 in array allows to cover a specific angle at which light needsto be provided. Due to thermal management and other considerations, thelights 14 may not be able to be placed contiguously butted in contactnext to one another. Depending on the LED layout pattern, one LED may beneeded to cover a specific angle not covered by other LEDs in the arrays13 under other lenslets 12. Further, while FIGS. 2A-2B show particulardimensions of the groups 23 of arrays 13 and particular distancesbetween lights 14 in the same array, other distances are dimensions arealso possible.

The LED array 13 and the microlens array 12 make up part of a lightfield illuminator sheet 30. The LEDs 14 in each array 13 are positionedso that their beams point at different directions (angles) at thelenslet 12 with which that array 13 is aligned. The direction of eachbeam from each of the lights 14 in each array ultimately depends on theoff-axis position of the light 14 relative to the optical axis of thelenslet 12 with which that array 13 is aligned. The direction of thelight from the LEDs 14 is always normal to the LED 14 emitting surface.The position of the LEDs 14 relative to the optical axis of the lenslet12 and the focal length of the lenslet 12 that the LED 14 is underdetermine the direction of the light from LED 14 refracted by lenslet12. The larger the off-axis position of a light 14 with respect to thelenslet 12 (with a light 14 being off-axis to the lenslet 12 if theoptical axis of the light 14 is not coincident with a mechanical centerof the lenslet 12), the larger the direction angle after the lenslet 12is produced. By having different lights 14 at different positions,varying illumination patterns can be produced.

Each of the lights 14 in each of the arrays 13 are individuallycontrolled by a Light Controller 15 executed by at least computingdevice 16 that is interfaced to the arrays 13. In one embodiment, thelights 14 are individually address via a central backplane, such as amatrix addressable backplane, though other arrangements are alsopossible. In one embodiment, the at least one computing device 16 couldbe connected to each of the lights 14 via a wired connection. In afurther embodiment, each of the lights 14 could be interfaced to awireless transceiver that receives commands from the at least onecomputing device 16 wirelessly (either directly from a wirelesstransceiver interfaced to the server 16 or via an Internetwork, such asthe Internet or a cellular network).

In a still further embodiment, the interfacing of the computing device16 to each of the lights 14 could be accomplished via a combination of awired and wireless connection. In addition, each of the lights 14 canreceive power, either through the backplane (with a wired connectionproviding power from a power source, such as an alternating currentpower source (such as an electric socket) or a direct current powersource (such as a battery included with the light sheet 30), thoughother ways of powering the light sheet 30 are possible. In oneembodiment, the wires that provide power to the light sheet 30 can runproximately to the wires via which the commands from the at least onecomputing device 16 are received, and in one embodiment, power could beprovided through the computing device 16 (with the computing device inturn interfacing to a power source such as an electric socket), thoughother connections are possible.

While the at least computing device 16 is shown as a server withreference to FIG. 1 , in a further embodiment, other types of computingdevices 16 can be used, such as laptop computers, desktop computers,mobile phones, and tablets, though still other types of computingdevices are possible.

The Light Controller 15 controls when each light 14 is turned on and offas well as the pulse width (with pulse width being the time that thelight 14 is on) and amplitude emitted by each light 14, thus controllingthe intensity of the light produced by each LED 14. The individual beamsfrom each LEDs form illumination pixels at the illumination plane orwithin a volume space, and their intensity can be modulated by the LightController 15 by controlling the light 14 producing the respective beam.Further, many illumination pixels will partially be superimposed on theneighboring illumination pixels over a large illumination space. Theincrements of the overlap are significantly smaller than the size of theillumination and by controlling which lights 14 are turned on at aparticular time, the Light Controller 15 can control where such overlapsoccur, which in turn allows to improve the overall quality of theillumination pattern produced (similarly to how high addressabilityprinting with lower resolution spots can be used to improve imagequality by removing jagged edges and achieving clustered lightdistribution for better half-toning). Further, by controlling which LEDs14 are turned on and the parameters of their use, the Light Controller14 can achieve better light utilization that improves lightingapplication efficiency.

The computing device 16 is interfaced to a storage 17, which can beinternal to the computing device 16 (such as internal memory of a laptopcomputer) or external to the computing device 16. The storage 17 storesdata 32 describing the characteristic of the light sheet 30, includingdata 18 describing the parameters of the microlens array 11, such as thedata describing the number of lenslets 12 in each of the microlensarrays 11, the size and shape of each lenslet 12, and the type of eachlenslet 12 in the array 11, though other types of data 18 are alsopossible. The light sheet data 32 further includes data 19 describingthe light array 13 aligned with each of the lenslets 13, including thetype of lights 14 in each of the array, the number of the lights 14 ineach array 13, the positioning of each of the lights 14 relative to thelenslet 12 aligned with the array 13 (such as the off-axis position ofthat light 14 relative to the lenslet 12), though still other types ofdata 19 are possible. If other components are present in the light sheet30, such as a spacer 25, a back reflector 24, and a light diffuser 26,characteristics of such additional components are included as part ofthe light sheet data 32.

The computing device 16 further executes a Light Identifier 21, whichobtains (such as by receiving from a user) and storing in the storage 17data 20 regarding a desired light illumination pattern, which can be afar-field illumination pattern or a light field distribution (thoughother types of illumination patterns are also possible). The desiredillumination pattern data 20 can describe where amount and intensity oflight to be shone by the sheet at particular places in the illuminationspace, as well as where illumination pixels should overlap. The data 20can describe the illumination pattern at a single time instance, astatic illumination pattern over a time period, or a dynamic desiredillumination pattern that changes over a time period. Still otherinformation can be included in the desired illumination pattern. TheLight Identifier 21 uses the desired light illumination pattern 22, thelight sheet data 32 (including the angles at which the lights 14 aredirected by their lenslets 14) to identify those of the lights 14 in thearrays that need to be turned on to create the desired illuminationpattern. FIGS. 5A-5F show, for purposes of illustration, differentillumination patterns 22 created through overlapping of illuminationpixels. The heavier-weighted dashed line in the FIGS. 5A-5F representthe intensity or the irradiance level at the illumination plane. Theillumination patterns can be far-field, as shown with reference to FIGS.6A-6F. FIG. 6A is an illustration of a ray trace 22 created by a smallsection of the sheet 30 when all LEDS 14 in that section of the sheetare on. FIG. 6B is an illustration of a ray trace 22 created by a smallsection of the sheet 30 when only on-axis LEDs 14 in that section areon. FIGS. 6C and 6D are illustrations of ray traces 22 created by thesheet 30 when only off-axis LEDs 14 in that section are on, with thelights 14 in FIG. 6C pointing in a different direction from thedirection of the lights 14 in FIG. 6D. FIGS. 6E and 6F are illustrationsof ray traces 22 created by a small section of the sheet 30 when allLEDs 14 in that section are on in Far-Field. FIG. 6H is an illustrationof ray traces 22 created by the sheet 30 by off-axis LEDs in theFar-Field region. FIGS. 6A-6F illustrate that there are multiple ways toilluminate the same object spatially, but the illumination angles may bedifferent depending on what LEDs 14 in combination with which lenslet 12are used. For example, if a vertical surface like a person's face needsto be illuminated, light at more vertical angles will create shadowswhere more horizontal angles will create less shadows and present abetter view of the face.

A significant portion of the light emitted by LEDs tends to be reflectedback to the LEDs by the surrounding environment, thus decreasing theefficiency of the LEDs (as the reflected light cannot be used for theprimary purpose of providing illumination) and heating up the LEDs. Thesheet includes several components to increase the light extraction. Onesuch component is the spacer 25 positioned between the microlens array11 and the light arrays 13. In one embodiment, the spacer 25 can be apyramidal, reflective, honeycomb-shaped spacer 25, as shown withreference to FIGS. 3A-3B, though other shapes of the spacer 25 are alsopossible. FIGS. 3A-3B are diagrams showing front (the side facing thelenslets 12) and back (the side facing the LEDs 14) of a pyramidal,reflective, honeycomb-shaped spacer 25 in accordance with oneembodiment. Similarly, on the opposite side of the light arrays 13 tothe side that faces the microlens array 11 is positioned a backreflector 24, which reflects the light emitted by the LEDs 14 towardsthe microlens array 11. In one embodiment, the spacer 25 and the backreflector 24 can be coated with aluminum or silver. In a furtherembodiment, the spacer 25 and the back reflector could be covered with awide band reflective coating. Still other coatings are possible. Whilein one embodiment, the spacer 25 and the back reflector 24 could havethe same coating, in a further embodiment, the spacer 25 and the backreflector 24 could have different coatings. FIG. 10 shows an expandedview of a light sheet 30 including the spacer 25 and the back reflector24 and with LEDs 14 being integrated into an LED plane 31 in accordancewith one embodiment. FIG. 11 shows the light sheet 30 of FIG. 10 withthe LEDs 14 emitting light. FIGS. 12A-B show simulated irradiancepatterns achieved using three light sheet 30 tiles that included thereflective pyramidal honeycomb-shaped spacer 25 and a back reflector 24.Full light sheets will consist of many light sheet tiles 30. FIG. 12Ashows the patterns when all of the lights 14 in the sheet 30 are onwhile the checkerboard-like pattern seen with reference to FIG. 12B wasproduced with only a subset of the lights 14 being on. FIGS. 13A-B showsimulated patterns, adjusted for human visual brightness perception,achieved using three light sheet tiles 30 that included the reflectivepyramidal honeycomb-shaped spacer 25 and the back reflector 24. WhereasFIGS. 12A-B show the illumination as a function of intensity orirradiance in terms of physical quantities like the energy or power perunit area, FIGS. 13A-B simulate what the human eye would see due tohuman vision system perceiving brightness on a logarithmic scale.Similarly to FIGS. 12A-12B, FIG. 13A shows the patterns when all of thelights 14 in the sheet 30 are on while the checkerboard-like patternseen with reference to FIG. 13B was produced with only a subset of thelights 14 being on. Note that the spacers 25 can be hollow or solid(i.e., filled) and can also have CPC (compound parabolic concentrator)or rectangular CPC shapes. They can be made reflective by usingreflective coatings like aluminum, silver, dielectric multilayerwide-band coatings or, if the spacer is solid, utilize TIR (totalinternal reflection) depending upon the design.

By extracting more diffuse light, the addition of the spacer and theback reflector increase the optical efficiency of the sheet 30. Theexact degree of the increase depends on the particulars of the spacer 25and the back reflector 24 used. For example, when an absorbinghoneycomb-shaped spacer 25 and absorbing back reflector are used, theoptical efficiency of the sheet 30 has empirically been shown toincrease by approximately 29%. Likewise, when a reflectivehoneycomb-shaped spacer 25 and reflective back reflector are used, theoptical efficiency of the sheet 30 has empirically been shown toincrease by approximately 52%. The overall optical efficiency achievedwith an aluminum coating on the honeycomb spacer 25 and the backreflector 24 and wide band antireflective coating on the honeycombspacer 25 is around 73.5%. If a perfect coating on the spacer 25 and theback reflector 24 (with a perfect reflective coating reflecting 100% ofthe light and a perfect anti-reflective coating transmitting 100% of thelight), the optical efficiency would rise to 90%.

As mentioned above, the exact improvement of the optical efficiencydepends on the particulars of the spacer 25 and the lenslets 12. Therefractive index of common glass and plastic optics is n˜1.5. Focallength of hemispherical lens of radius R, f˜R/(n−1)˜2R, andhoneycomb-shaped spacer 25 is needed to eliminate stray light. For f˜2R,f/#˜1, NA˜0.5, optical efficiency˜0.25. For an LED 14 placed at frontfocus of lenslet 12 and positioned off-axis by distance d, the pointingangle of the exit beam is given by θ_(pointing)˜arctan(d/f). For an LEDof diameter D, placed at the front focus of lens, the full divergence ofthe exit beam is given by ƒ_(divergence)˜arctan(D/f). FIG. 4 is adiagram illustrating the pointing angle and the divergence angle.Off-axis lenslet 12 sections can also be used to increase the range ofangles that can be produced by light sheet 30, as can be seen withreference to FIG. 18 . FIG. 18 is a diagram showing a light 14 Beampointing towards off-axis lenslets 12 in accordance with one embodiment.Off-axis lenslet 12 sections can also be used to vary the rangeaddressable angles across the light sheet surface.

Depending on the precise illumination pattern desired, the light emittedby the lights 14 may need to be diffused to achieve the desiredqualities. In a further embodiment, in addition to the back reflector 24and the honeycomb spacer 25, the sheet 20 can include a light diffuser26 positioned above the microlens array 11 (relative to the orientationshown with reference to FIG. 1 ), facing the side of the microlens array11 that is opposite to the side facing the LED array 13. The lightdiffuser 26 diffuses the light after the light passes through thelenslets 12, which helps to achieve complete diffusion of LED spots(with LED spots being. bright spots that are too bright to becomfortably viewed by the naked eye; in addition to viewing objectsilluminated by the light, the lighting fixture can fall within the fieldof vision, which is what is commonly meant by glare). To achieve thesubstantially complete diffusion of the LED spots, thickness of thediffuser 26 needs to be substantially equal to the LED pitch (distancebetween the pixels created by the LEDs 14 in the array 13). Empirically,when the diffuser 26 thickness is between 1.5 to 2 times the LED pitch,the individual LED spots begin to be resolved but the brightness of thespots is reduced by about 25 times.

As mentioned above, the illumination achieved using the system 10 can bedynamic, differentiating what is achievable from preexisting lightingtechnology. FIG. 7 illustrates an example of conventional beam steering(prior art), which has high glare and requires moving parts. FIG. 8illustrates an example of light shifting (prior art), published in U.S.Department of Energy Office of Energy Efficiency & Renewable Energy,2019 Lighting R&D opportunities, January 2020, the disclosure of whichis incorporated by reference, whose glare is still far from optimal(high glare) and requires moving parts. FIG. 9 is an illustration ofdynamic light sheets achievable using the system 10, which has animproved light application efficiency (LAE), with no moving parts, andlower glare compared to the techniques illustrated with reference toFIGS. 7 and 8 . The dynamic light sheet is uniquely capable of digitallyimproving lighting application efficiency (LAE) by only delivering lightto where it is needed, providing illumination that possesses thespectral content that is advantageous to the human visual system, andadjusting the light intensity at efficacious levels.

Returning to FIG. 1 , the at least one computing device 16 can also beinterfaced to one or more sensors 51. The sensors 51 can be locatedeither in the proximity of the light sheet 30 or on the light sheet 30directly. The sensors 51 can detect one or more objects in the way ofthe desired illumination pattern and an incomplete generation of thedesired illumination pattern, thus being able to provide additionalfeedback regarding the illumination created by the system 10 as well anyobstacles in the way of the light produced by the system 10. Suchsensors 51 can include motion sensors, light sensors, and occupancysensors, though other kinds of sensors 51 are also possible. The sensors51 can also be other kinds of environmental sensors. For example, thesensors 51 could sense the light level in the surrounding of the lightsheet 30 (such as in a room where the sheet 30 is located). The sensor51 could also be a temperature sensor, and sense temperature either inthe surrounding environment (if located in proximity to the light sheet30) or of the light sheet 30 (if located on the light sheet 30).Similarly, a sensor 51 could be a moisture sensor sensing moisture levelin the environment surrounding a light sheet 30. Still other kinds ofenvironmental sensors are possible.

The sensors 51 could be interfaced to the at least one computing device16 through a wired connection, a wireless connection, or a combinationof wired and wireless connection (including through use of a network,such as an Internetwork such as the Internet or a cellular network). Forexample, if the sensors 51 are located on the light sheet 30, thesensors 51 could be interfaced to the at least one computing device 16through wires that run proximately to the wires through which the lightsheet 30 receives power, commands, or both. Likewise, the sensors 51could be interfaced to a wireless transceiver that transmits the data 52from the sensors to a wireless transceiver interfaced to the at leastone computing device 16. Still other kinds of interfacing between thesensors 51 and the wireless transceiver are possible.

The data 52 provided by the sensors 51 can be used by the lightidentifier 21 to either the lights 14 that need to be turned on toeither create the desired illumination pattern 20 (if the data isreceived before the lights 14 are first turned on) for a first time, orto remedy encountered problems in creating the desired illuminationpattern 20 if the data 52 indicates that after the lights 14 have beenturned on initially, the pattern 20 has not been achieved (such as dueto an incorrect identification of the lights that need to be turned on)or the pattern 20 is being disrupted (such as due to obstacles thatappeared in the way of the light being projected). The lights controller15 can turn on the lights 14 identified based on the data 51.

The data 52 from the sensors 51, such as environmental sensors, can alsobe used by the at least one computing device 16 to modulate theintensity of the light emitted by the identified LEDs 14, and how longthe lights are on. For example, if there is a high level of naturallight in a room where a light sheet is located, the intensity level tocreate a desired illumination 20 may be higher than in a dark room.Likewise, as temperature can affect light output of an LED 14, theintensity of the emitted light can be modulated based on the sensedtemperature. Further, if the temperature of a light sheet 30 exceeds apredetermined threshold, all of the lights 14 in that light sheet 30 canbe turned off to avoid a possible fire danger. Similarly, as thecreation of an illumination pattern 20 can be affected by moisture level(including foggy conditions), the intensity of the emitted light 16 canbe modulated based on the sensed moisture level. Thus, due to having afeedback mechanisms, the system 10 can function programmatically andautonomously, being able to maintain a desired illumination patternwithout continued human input.

As mentioned above, while the one or more computing devices 16 are shownas a server, other types of computer devices are possible. The computingdevices 16 can include one or more modules for carrying out theembodiments disclosed herein. The modules can be implemented as acomputer program or procedure written as source code in a conventionalprogramming language and is presented for execution by the processors asobject or byte code. Alternatively, the modules could also beimplemented in hardware, either as integrated circuitry or burned intoread-only memory components, and each of the computing devices 16 canact as a specialized computer. For instance, when the modules areimplemented as hardware, that particular hardware is specialized toperform the computations and communication described above and othercomputers cannot be used. Additionally, when the modules are burned intoread-only memory components, the computer storing the read-only memorybecomes specialized to perform the operations described above that othercomputers cannot. The various implementations of the source code andobject and byte codes can be held on a computer-readable storage medium,such as a floppy disk, hard drive, digital video disk (DVD), randomaccess memory (RAM), read-only memory (ROM) and similar storage mediums.Other types of modules and module functions are possible, as well asother physical hardware components. For example, the computing device 16can include other components found in programmable computing devices,such as input/output ports, network interfaces, and non-volatilestorage, although other components are possible. In the embodiment wherethe computing devices 16 are servers, the server can also be cloud-basedor be dedicated servers.

The digital control of individual LEDs 14 allows customization of thelighting provided to the particular environment in which the lighting isprovided. FIG. 14 is a flow diagram showing a method 40 for light fieldilluminator sheet-based dynamic lighting control in accordance with oneembodiment. The method 40 can be implemented using the system 10 of FIG.1 . Initially, light sheet data 32, including the microlens array data18 and the light array data, is obtained (step 41). Desired illuminationpattern 20 is obtained, such as through being received from a user (step42). Which of the lights 14 need to be turned on, for what duration, andat what time, is determined using the light sheet data 32, the desiredillumination pattern 20, and optionally data 52 from one or more sensors51, as also described above with reference to FIG. 1 (step 43). Thelights 14 are turned on and off based on the determination (step 44).Optionally, data 52 from one or more sensors 51 is received by the oneor more computing devices 16 (step 45) and if an adjustment of whichlights 14 are turned on is necessary as determined based on the data(step 46), the method 40 returns to step 43. If no adjustment isnecessary (step 46), the method 40 ends.

The system 10 and method 40 allow to achieve a high light applicationefficiency and increased control over the provided light, as can be seenfrom FIGS. 15A-15B and 16A-16B, which describe simulations ofillumination achievable using a particular light sheet tile 30. FIGS.15A-15B are diagrams describing details of the particular light sheettiles used for an illumination simulation. FIGS. 16A-16B are diagramsillustrating the illumination patterns simulated achievable with threelight sheet tiles 30 of FIGS. 15A-15B. The sheet 30 shown with referenceto FIGS. 15A-15B includes an absorbing spacer 25. Using a reflectivespacer 25 can help to extract more light, but can also cause undesirableartifacts. FIGS. 17A-17B show simulated patterns, adjusted for humanvisual brightness perception, achieved when all of the lights 14 in thesheet 30 are on (FIG. 17A) and when only a subset of the lights 14necessary to produce the checkerboard-like pattern are on (FIG. 17B).The sheet 30 simulated with reference to FIGS. 17A-17B includesreflective spacers 25. The reflective spacers 25 extract more light butproduce artifacts. However, since the lighting sheet 30 produces diffuseillumination (as opposed to images), the artifacts would be blended in away that is acceptable. FIG. 61 is an illustration of a ray trace with apresence of a low-level artifact created by a small section of thesheet. As is illustrated by FIG. 6I, such artifacts are relativelyimperceptible.

The simulations shown with reference to FIGS. 12A, 12B, 13A, 13B, 16A,16B, 17A, and 17B use three tiles 30 to illustrate the tiles' 30 basiccapabilities and to make the simulation computationally tractable.However, the space and area between and around the tiles 30 could befilled with other tiles 30 making a large area contiguous sheet, whichallows to obtain much more smoothly varying and subtly changingillumination patterns, angular content, spectral content, and greaternumber of intensity levels will be obtainable.

While the invention has been particularly shown and described asreferenced to the embodiments thereof, those skilled in the art willunderstand that the foregoing and other changes in form and detail maybe made therein without departing from the spirit and scope of theinvention.

1. A system for sensor-guided dynamic lighting output, comprising: amicrolens array comprises a plurality of lenslets; an array of solidstate light sources aligned with each of the lenslets; one or moresensors configured to collect data; a computer in control of each of thelight sources and interfaced to the one or more sensors, the computercomprising at least one processor, the computer configured to: obtain adesired illumination pattern comprising at least one of a desiredfar-field illumination pattern and a desired light field distribution;identify based on at least some of the sensor data those of the lightsources that need to be turned on to generate the desired illuminationpattern; and control the identified light sources to generate thedesired illumination pattern.
 2. A system according to claim 1, whereinthe sensor data comprises data regarding objects in the way of thedesired illumination pattern.
 3. A system according to claim 2, whereinthe sensors comprise one or more of motion sensors, light sensors, andoccupancy sensors.
 4. A system according to claim 1, wherein themicrolens array, the solid state light sources, and one or more of thesensors are comprised in a light field illuminator sheet.
 5. A systemaccording to claim 1, wherein one or more sensors are wirelesslyinterfaced to the computer.
 6. A system according to claim 1, thecomputer further configured to: detect using at least some of the sensordata a disruption of the desired illumination pattern; and adjust whichof the lights sources are turned on based on the disruption and at leastsome of the sensor data.
 7. A system according to claim 1, the computerfurther configured to: modulate an intensity of a light generated by theidentified light sources based on at least some of the sensor data.
 8. Asystem according to claim 7, wherein the sensors comprise one or more ofa temperature sensor, a light level sensor, and a moisture level sensor.9. A system for sensor-based dynamic lighting output generation andmodification, comprising: a microlens array comprises a plurality oflenslets; an array of solid state light sources aligned with each of thelenslets; one or more sensors configured to collect data; a computer incontrol of each of the light sources and interfaced to the one or moresensors, the computer comprising at least one processor, the computerconfigured to: obtain a desired illumination pattern comprising at leastone of a desired far-field illumination pattern and a desired lightfield distribution; identify those of the light sources that need to beturned on to generate the desired illumination pattern; command theidentified light sources to turn on to generate the desired illuminationpattern; detect using at least some of the sensor data that anillumination pattern generated by the commanded light sources differsfrom the desired illumination pattern; and adjust which of the lightssources are turned on based on the detection and at least some of thesensor data.
 10. A system according to claim 9, wherein the sensor datacomprises data regarding objects in the way of the desired illuminationpattern.
 11. A system according to claim 10, wherein the sensorscomprise one or more of motion sensors, light sensors, and occupancysensors.
 12. A system according to claim 11, wherein the microlensarray, the solid state light sources, and one or more of the sensors arecomprised in a light field illuminator sheet.
 13. A system according toclaim 9, wherein the difference between the generated illuminationpattern and the desired illumination pattern is due to one of anincomplete generation of the desired illumination pattern and adisruption of the desired illumination pattern.
 14. A system accordingto claim 9, wherein the difference between the generated illuminationpattern and the desired illumination pattern is due to one of anincomplete generation of the desired illumination pattern and adisruption of the desired illumination pattern.
 15. A system accordingto claim 9, the computer further configured to: modulate an intensity ofa light generated by the identified light sources based on at least someof the sensor data.
 16. A system according to claim 9, wherein thesensors comprise one or more of a temperature sensor, a light levelsensor, and a moisture level sensor.
 17. A system for sensor-baseddynamic lighting output intensity modulation, comprising: a microlensarray comprises a plurality of lenslets; an array of solid state lightsources aligned with each of the lenslets; one or more sensorsconfigured to collect data; a computer in control of each of the lightsources and interfaced to the one or more sensors, the computercomprising at least one processor, the computer configured to: obtain adesired illumination pattern comprising at least one of a desiredfar-field illumination pattern and a desired light field distribution;identify those of the light sources that need to be turned on togenerate the desired illumination pattern; command the identified lightsources to turn on to provide light to generate the desired illuminationpattern; modulate an intensity of the light generated by the commandedlight sources based on at least some of the sensor data.
 18. A systemaccording to claim 17, wherein the microlens array, the solid statelight sources, and one or more of the sensors are comprised in a lightfield illuminator sheet and one of the sensors comprised on the sheet isa temperature sensor, the computer further configured to: receive atemperature associated with the sheet from the temperature sensor;compare the temperature to a threshold; and turn off all of thecommanded light sources based on the comparison.
 19. A system accordingto claim 17, wherein the sensors comprise one or more of a temperaturesensor, a light level sensor, and a moisture level sensor.
 20. A systemaccording to claim 17, wherein one or more sensors are wirelesslyinterfaced to the computer.